Leonardo da Vinci sketched a ball bearing to help a rotating shaft move more smoothly.
Leonardo’s notebooks contain designs for reducing friction with rolling balls. In a bearing, balls sit between an inner and outer surface, replacing much of the sliding friction between two surfaces with rolling friction. His sketches are often cited as an early recorded example of the ball-bearing principle.
The idea was especially useful for rotating machinery, where friction could waste energy and cause wear. Leonardo’s drawings show an attempt to keep the balls separated so they would not bunch together and interfere with one another.
Leonardo did not invent every form of bearing, and ancient machines had used rollers and related friction-reducing ideas. Nor did his sketches immediately lead to mass-produced precision bearings. Modern bearings require accurate materials, dimensions, lubrication, and manufacturing. Leonardo’s contribution was an important early mechanical design, not a complete industrial bearing system.